NATURAL-CONVECTION IN HORIZONTAL ANNULUS FILLED WITH AN ANISOTROPIC POROUS-MEDIUM

The natural two-dimensional convection taking place between horizontal concentric cylinders filled with a satured anisotropic porous medium is studied numerically. The anisotropy concerns exclusively the permea bility. Isothermal boundary conditions are applied on both inner and o uter boundaries, with the outer boundary being warmer. The effects of the anisotropic permeability ratio K, of the orientation angle of the principal axes defined by gamma, and of the Rayleigh number Ra on th e flow and heat transfer are investigated. Results indicate that a net circulating flow around the annulus is generated, except for values o f gamma that preserve the symmetry of now conditions with respect to t he vertical diameter. It is also shown that the anisotropic part of th e resistivity tensor is equivalent to a magnetic resistivity tensor.